<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<style>
    div {
        font-size: 10px;
        font-weight: 10px;
    }
</style>
<body>
    <div class="click">点击</div>
</body>
<script>
    let cli = document.querySelector('div')
    cli.onclick = function()
    {
        let CurFontSize = parseInt(this.style.fontSize);
        console.log(isNaN(CurFontSize));
        CurFontSize += 10;
        this.style.fontSize = CurFontSize + 'px';
    }
</script>
</html>